Delay in compaction and importance of the lime fixation point on the strength and compaction characteristics of soil

The importance of the lime fixation point on the strength of fine-grained soil hardly needs to be stressed. The improvement in strength of soils with lime contents below and above the lime fixation point occurs by different mechanisms. Further, the strength is also influenced by moulding water content and dry density. The time lag between wet mixing and compaction plays a major role in the application of lime to fine-grained soils. This paper highlights the importance of the lime fixation point on the compaction characteristics of expansive Indian black cotton soil. The effect of delay below, at and above the lime fixation point on the compaction and the strength characteristics is presented. Below the lime fixation point, lime addition steeply decreases the maximum dry density and marginally improves the strength. Here the strength is significantly influenced by the moulding water content. Delay between wet mixing and compaction is less critical below the lime fixation point. For soil with a lime content above the lime fixation point there is no further change in the compaction curve. The strength improves considerably above the lime fixation point and is not controlled by moulding water content. Further delay in compaction for the soil above the fixation point steeply reduces the maximum dry density and strength. At about the lime fixation point the effect is in between the two extremes.